Answer:
B
Explanation:
Option B is the correct answer. When you add 7 in front of the O2 in the left side, and then you add 4 and 6 in front of NO2 and H2O respectively, the number of oxygen atoms is the same in both sides.
sorry I have no idea what the answer is
it rusts
MgO + 2HBr → MgBr2 + H2O